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Questions and answers on fluoridated water

What is fluoride, and why do we need it?

Fluoride is a naturally occurring mineral. Decades ago, health officials realized that areas with high levels of fluoride in their water also had less tooth decay, spurring efforts to add fluoride in areas with lower levels. When you eat sugar or other refined carbohydrates, bacteria in the mouth produces acid that removes minerals from the surface of the tooth. Fluoride helps remineralize the tooth surface and prevent cavities, according to the federal Centers for Disease Control and Prevention.

Which areas fluoridate their water supply?

About 72 percent of people in the United States who live in areas with public water systems have fluoridated water. In Florida, about 78 percent do. Residents in Hillsborough have fluoridated water, while Pasco County and large areas of Hernando County except Brooksville don't. Pinellas County plans to end water fluoridation, but St. Petersburg, Gulfport, Dunedin and Belleair will not be affected.

Which areas don't fluoridate water, and why?

The five states with the lowest percentage of residents who have access to fluoridated water are Hawaii, New Jersey, Oregon, Louisiana and Montana. Cities that recently decided to end fluoridation include Spring Hill, Tenn.; Pottstown, Pa.; San Jose, Calif.; and Fairbanks, Alaska. France, Germany and Japan are among countries that don't add fluoride to the water supply.

Governments that don't use it cite concerns such as health impacts or effectiveness.

What impact has fluoridated water had in the United States?

Federal health officials consider fluoridation among the 10 great public health achievements of the 20th century. It is associated with a 25 percent reduction in tooth decay, said Dr. William Bailey, chief dental officer of the U.S. Public Health Service and acting director of the division of oral health at the CDC.

Are there health risks from getting too much fluoride?

Yes. Consuming higher-than-recommended amounts of fluoride during the teeth-forming years (age 8 and younger) can cause dental fluorosis, which appears as white spots on the tooth surface. It usually does not weaken the teeth and can be treated by chemical abrasion, bonding or crowning, said Dr. Rodney Holcombe, a Tampa dentist.

Ingesting very high doses of fluoride (far more than what's in drinking water) for a long time can lead to weak or brittle bones, a disease known as skeletal fluorosis.

How much fluoride is too much?

The highest level of fluoride allowed in public water systems is 4 milligrams per liter, set by the Environmental Protection Agency. Bailey cited a National Research Council report that showed that among children drinking at that level, 10 percent might have a severe case of fluorosis.

But most systems, including in the bay area, have much less fluoride, following a new U.S. Public Health Service recommendation of 0.7 mg per liter. At that level (and even somewhat above), Bailey said, adverse effects aren't seen.

Is the water supply the best way to deliver fluoride?

Health officials think so, because people take in water throughout the day, getting cavity protection. It also helps protect people who cannot afford regular dental care, a growing population in the current economic climate. "You don't have to remember to do anything," Bailey says. "It reaches people of all socioeconomic groups."

What do I do if I don't have fluoridated water?

Dr. Craig Oldham, president-elect of the Hillsborough County Dental Association, recommends fluoride supplements for children 12 and under who live in areas without fluoridated water. "Daily brushing is not enough," he said, pointing out that ingesting fluoride — not just placing it on the teeth — is essential for tooth formation in children. Also, research has found that as people age and saliva production declines, fluoridated water also is protective.

Times staffers Stephen Nohlgren and Natalie Watson contributed to this report. Richard Martin can be reached at or (813) 226-3322.

Questions and answers on fluoridated water 10/05/11 [Last modified: Wednesday, October 5, 2011 10:07pm]
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